The objective of the proposed research is to determine principles of sensory coding of spatial information by examining how the somatosensory system integrates inputs from multiple points on the skin. Neurophysiological and psychophysical studies have shown that the nervous system often performs complex spatial and intensive transformations of these multiple point stimuli which amplify or diminish their intensity, and increase or decrease the spatial resolution of the pattern. The development of chronic single unit recording techniques, together with operant behavioral methods for measuring sensory discriminative abilities in monkeys, will permit me to study the neurophysiological and psychophysical parameters of the transformation of spatial information in the same animal. The neurophysiological representation of light tactile stimuli presented simultaneously at two or three points on the skin will be traced from the cuneate nucleus, through the thalamus, to the primary and secondary somatosensory cortex in awake, behaving Rhesus monkeys. This investigation may yield answers to the following questions: How do neural networks in the relay nuclei integrate and transform spatial and intensive properties of multiple point stimuli? How does the nervous system resolve two points on the skin? Are perceptual thresholds determined by receptor properties or by central patterns of activity? What is the effect of attention on spatial integration? Answers to these questions will be useful not only for understanding somatosensory function but may be of general applicability of multiple channels of information in other sensory systems.